best low light performance

More thoughts:

What exactly is a low light level? Here's a picture of our poly silicone panels on a an overcast day, it looked pretty cloudy to me. Is this a 200W/m2 day?:


Overcast (Small) by Bdosborn, on Flickr

The panels were doing surprisingly well - 220 watt array laying flat with 74 watts output:


Meter (Small) by Bdosborn, on Flickr

How cloudy would it need to be to make to make a thin film solution worthwhile? Would it ever make sense with the limited size of an RV versus a utility sized grid? I dunno but for me the small size of our roof made the PSI approach obvious...

Bruce

Here's the IV curve for a unisolar 124 watt.



Here's the IV curve for the 240W panel PT posted a link to (sorry, that's as big as the photo is)



Double the output of the Unisolar panel on the 200 w/m2 to compensate for a 124w panel versus a 240w and you get approximately the same output as the 240w panel at 200 w/m2. I guess the question is what is the average irradiance of your location? Below 200 w/m2, it *might* make sense to go with the Unisolar but I wouldn't design for the extreme shoulders of the local insolation levels.

The big difference is the 240 watt panel is ~18 sqf versus ~42 sqf for 248 watts of Unisolar panel.

Bruce

Unisolar Efficiency by Bdosborn, on Flickr

Yes, Unisolar is more efficient at lower light levels. Unfortunately, efficiency decrease with increased irradiance so you actually have decreased unit output on sunny days. This doesn't address partial shading, angle to the sun or high heat conditions but I don't see much of a reason to go with Unisolar based on low light performance. The typical poly and mono panel is still going to outperform the unisolar, watt for watt, in low light conditions at STP.

From the link posted earlier:

Unisolar Linky

Bruce

pianotuna wrote:
Hi harold,

The unisolars I have are not the flexible type. But if they were, they are still UV protected, so your comment is "out to lunch". Please do continue to be off topic and make misleading comments.

harold1946 wrote:
The other is what pianotuna has,flexable type, with the plastic coating that UV will deteriorate and has been the main issue.

Are you saying that your panels are rigid framed with glass.
All I have asked is that there be some supporting documentation for the claims being made.
What type of UV protection?
I have not been off topic. I have answered the original question using the industry standard PV evaluation tables, of which all thin film amorphous panels are rated the lowest in the industry.
I welcome any independent evaluation that indicates differently.

pianotuna wrote:
Hi harold,

The unisolars I have are not the flexible type. But if they were, they are still UV protected, so your comment is "out to lunch". Please do continue to be off topic and make misleading comments.

harold1946 wrote:
The other is what pianotuna has,flexable type, with the plastic coating that UV will deteriorate and has been the main issue.

Are you saying that your panels are rigid framed with glass?
All I have asked is that there be some supporting documentation for the claims being made.
What type of UV protection?
I have not been off topic. I have answered the original question using the industry standard PV evaluation tables, of which all thin film amorphous panels are rated the lowest in the industry, no matter who the manufacturer is.
I welcome any independent evaluation that indicates differently.
I am not the one making un-substantiated claims.
If thin film panels are superior, why are you seeking other types?
Makes no sense why one would want to transition from panels that "are the best in lowlight conditions", to anything regarded as inferior.

Hi harold,

The unisolars I have are not the flexible type. But if they were, they are still UV protected, so your comment is "out to lunch". Please do continue to be off topic and make misleading comments.

harold1946 wrote:
The other is what pianotuna has,flexable type, with the plastic coating that UV will deteriorate and has been the main issue.

The point is not moot. Although they are no longer being produced they are still available in the retail market.
I am not referring to Unisolar, rather all of the flexable thin film panels in general.

I suppose you have a source that supports 40 years + longevity of thin film. Please share.

Hi harold,

Misinformation seems to be happening. Uni-solar panels have been around for years. Some thin film do deteriorate. They should be avoided. Uni-solars do not fail any sooner than glass covered panels and are less susceptible to impact damage than a glass covered panel. The point is moot, for as you correctly pointed out Unisolar doesn't produce panels any more.

I disagree about why they went under. I believe it was because of foreign based factories using the technology and design that Uni-solar developed and undercutting the price.

To quote Pogo "We have met the enemy and he is us"

HiTech wrote:

harold1946 wrote:
You read into it more than was stated. I said there were better choises for efficiency than Thin film amorphous panels which have the worst conversion efficiency rating in the PV industry, nothing more.
I rated the different types using the industry standard tier scale.
I was asked about what type of solar panels I have and answered that I have The Sony Hybrid. I made no personal claim, mearly stated they have the highest conversion efficiency rating in the industry, which can be varified.
I am not responsible for the reading comprehension or interpretation by others.
The consept of thin film technology is an exelent one and may yet prove to be the furure of PV. As presented in its current form it is the the highest cost per watt for the lowest return in output of anything in the industry, irrespective of available light.

If one wants to get very technical and dig into some interesting information, I suggest studying the affects of ambient temperature on PV panels.

Don't go there, thin film tends to do well ;) at least the Unisolars do (triple junction thin film, with each layer absorbing a different light frequency).

Jim

I feel its only fair to go there to inform others that there are better choises than thin film technology. Not only in "bang for the buck", but also in terms of efficiency, longevity, and power produced.
Are you aware that there are two types of thin film construction?
One uses a conventional frame and glass, and is the best of the two.
The other is what pianotuna has,flexable type, with the plastic coating that UV will deteriorate and has been the main issue.
It does not matter what the ability is to absorb light if the light can not get through the cloudy plastic layer.

Lots of reasons I am sure, including the glut of PVs on the market. And the full sun efficiency gap to be sure. But as thin film devices go, they were the ones I picked after a bit of research. Better will come.

Jim